1. Field of the Invention
This invention relates in general to a cellular communication system, and more particularly to a location update method and an inter Core Network (CN) entity handover method, and further more particularly to a location update method and an inter-SGSN handover method in a 3rd Generation (3G) cellular system.
2. Description of Related Art
Cellular systems have had a direct effect on the lives of millions over the past few years. For the first time, people are able to make and receive phone calls without being tied to a specific location. Mobile phones, as part of the cellular systems, have allowed people to break the tie between location and access to communication. Mobile phones have also allowed people to reach another who is in move. With the development in cellular systems, people are allowed to reach another who is mobile in anywhere at anytime.
The first generation of mobile communication systems were born in the early 1980s. The marriage of radio and telephone technologies gave birth to mobile phones and triggered a turning point in telecommunications. Adding radio access to a telephone network meant that for the first time in history, the concept of a telephone being at a fixed point in the network was no longer valid. The benefits of being able to make and receive telephone calls anywhere had appeal to business peoplexe2x80x94the original market. In the first generation of cellular networks, analog wireless technology were used for the user connection (called the xe2x80x9cair interfacexe2x80x9d). Every voice channel had its own narrow frequency band, using a technology called Frequency Division Multiple Access (FDMA).
However, as the demand for mobile phones grew and grew, regularly exceeding forecasts, it became obvious that the available radio spectrum would not be adequate to accommodate the expected numbers of mobile phone users. The digital technology became the solution to the problem. The answer lay in new digital wireless technologies that allow larger numbers of mobile subscribers to be supported within a given frequency allocation. Time Division Multiple Access (TDMA) technology is used in which a broader frequency channel is divided into intermittent time-slots, i.e. several calls share the same frequency channel at any one time. The digital technology also offered other important benefits. It provided better voice quality and improved security against unauthorized eavesdropping. Another technology, Code Division Multiple Access (CDMA) has also been developed subsequently to increase capacity.
The first and second generation mobile communication systems were mainly set to support voice communications, although today""s mobile phones can also be used for data transfer at rates that are acceptable for relatively low-speed data applications such as sending and receiving of faxes and e-mail. However, these systems do not support high-speed data or video applications. The third generation mobile communication system is being developed to remove the bandwidth bottleneck and support a whole new range of voice, data, video, and multimedia services. For example, smart messaging is bringing Internet services to every mobile user""s fingertips. As people become used to the freedom that mobile communications have provided, they will become more demanding about the information and services required to benefit their lives.
The demand by consumers all over the world for mobile communications service continues to expand at a rapid pace and will continue to do so for at least the next decade. To satisfy such demand, more and more innovative mobile telecommunications networks are being built in this growing industry.
In the 3rd generation cellular systems, many practical techniques are being developed over the past few years. The mobile telecommunication network comprises switching functions, service logic functions, database functions, and Mobility Management (MM) functions that enable subscribers to be mobile. These are some of the functions provided by Mobile Switching Centers (MSCs) for serving Circuit Switched (CS) connections, by Visitor Location Registers (VLR) for serving CS connections, or by other network entities, for example, Serving GPRS Support Node (SGSN) for Packet Switched (PS) connections (GPRS refers to General Packet Radio System).
Generally, the database in the Core Network (CN) keeps tracks of the location of Mobile Stations (MSs). In one case, the CN comprises both entities, MSC and SGSN, to implement such database. Each of the MSs can have a CS or PS connection service from the CN by sending radio signals to its Base Station (BS). Each of the BSs is controlled by a Radio Network Controller (RNC) which connects to the CN.
When a MS with an active connection moves from one area to another, a handover (also known as handoff) procedure is performed between the BSs During a handover procedure, a CN entity can operate in two different ways: one is called anchoring, and the other is called floating. In an anchoring procedure, the control of the MS remains in the first network entity where the connection between the MS and the CN was started, whereas in a floating procedure, the control of the MS is changed along with the move of the MS. FIG. 6 shows an anchoring procedure. FIG. 7 shows a floating procedure.
One of the problems in developing a 3rd generation cellular system is location update when a MS, e.g. with an active connection, moves from one area to another. This problem does not appear in a 2nd generation cellular system due to the fact that the 2nd generation cellular system does not use macro diversity and Iur-interface in the systems. In a conventional 2nd generation cellular system, e.g. GSM (Global System for Mobile communications), only one Base Station (BS) receives radio signals from a MS. Accordingly, when a MS moves from one area to another, the MS knows which BS controls the MS so that a location update can be performed by communicating between the MS and the CN via this BS. However, in a 3rd generation cellular system, to increase the capacity of the data transmission, a macro diversity and Iur-interface concept are introduced in the system. In particular, multiple Base Stations can receive radio signals from and to a MS, and due to the Iur-interface, the BSs are not necessarily connected to one Radio Network Controller (RNC). A Serving RNC (SRNC) informs the BS which MS is under its control and is connected to the CN entities in the CN. When a MS moves, the control to the MS may be changed from one RNC to the other RNC in a fashion that the MS may not be involved. As a result, when a MS moves from one area to another, the MS does not know when the SRNC is changed. If the MS sends a location update before the SRNC is changed, the location update may be sent to a wrong CN entity.
Another problem in a 3rd generation cellular systems is that during an active PS connection from a SGSN, a MS may move to an area where the SGSN should be changed. For instance, when a SRNC for a MS is changed, the new SRNC is connected to the new SGSN. In a 3rd generation cellular system, changing of a controlling SGSN needs to be executed in the CN because the MS does not know when it has entered in the new SGSN area and which RNC controls the MS due to the possible macro diversity and Iur-interface. In the existing 2nd generation cellular system, the new SGSN has to request from the old SGSN all information after the new SGSN receives a location update from the MS. During such a SGSN handover, all the radio related entities in RNCs, BSs, MSs, etc., have to be released. Thus, it is inefficient to perform an inter-SGSN handover.
Therefore, it can be seen that there is a need for an initiation scheme for location update of a MS in a 3rd generation cellular system. It can also be seen that there is a need for an inter-SGSN handover scheme in a 3rd generation cellular system.
To overcome the problems in the prior art described above, and to overcome other problems that will become apparent upon reading and understanding the present specification, the present invention discloses a scheme for providing a notification to a Mobile Station (MS) to initiate a location update in a 3rd generation system. Further, the present invention discloses a scheme for providing update of location of the MS to a new Core Network (CN) entity via interface between the CN entities. Furthermore, the present invention discloses a scheme for providing update of location of the MS to a new CN entity via interface between a CN entity and a Serving RNC (SRNC). Moreover, the present invention discloses a scheme for providing an inter Core Network (CN) handover, e.g. inter-SGSN handover, in a 3rd generation cellular system.
In the present invention, several schemes for notifying the MS to initiate a location update from the MS to a Core Network (CN) while the MS is having an ongoing connection are disclosed. In one embodiment, the present invention provides a notification to the MS when there is a Serving Radio Network Controller (SRNC) relocation, which includes the following steps of: serving the MS by a first RNC; moving the MS from a first area to a second area wherein service in the first area is controlled by the first RNC, and service in the second area is controlled by a second RNC; serving the MS by the second RNC, so that the control of the MS is changed from the first RNC to the second RNC; determining by the second RNC whether a notification to the MS for the location update is needed based on factors such as configuration of the CN which is connected to the plurality of RNCs and/or the types of connection that the MS is having, etc.; and notifying, by the second RNC, the MS that a location update from the MS should be performed; and if the notification to the MS for the location update is determined by the second RNC to be needed, updating a location of the MS in the CN. Alternatively, the RNC does not determine whether a notification to the MS for the location update is needed. It is up to the MS to determine whether the location update should be made. In this case, the second RNC directly notifies the MS that a location update from the MS should be performed, and if the MS decides to update the location, MS sends the location update to the CN.
In an alternative embodiment, the present invention provides an update of the location of the MS from a SRNC to a new idle CN entity via an interface between the SRNC and the new idle CN entity when there is a Serving Network Controller (SRNC) relocation, which includes the following steps of: serving the MS by a first RNC; moving the MS from a first area to a second area wherein service in the first area is controlled by the first RNC, and service in the second area is controlled by a second RNC; serving the MS by the second RNC, so that the control of the MS is changed from the first RNC to the second RNC; determining by the second RNC whether the location update is needed based on factors such as configuration of the CN which is connected to the plurality of RNCs and/or the types of connection that the MS is having, etc.; and sending update of the location of the MS by the second RNC to a new idle CN entity (an idle CN entity is a CN entity which does not have an active connection for that particular MS) via an interface between the SRNC and the new CN entity. The CN entity can be a MSC/VLR (Mobile Switching Center/Visitor Location Register) or a SGSN (Serving GPRS Support Node, GPRS is General Packet Radio System). Alternatively, the CN entity determines whether the location update is needed. If the location update is needed, the RNC then sends the location update to the new CN entity via the interface between the SRNC and the new CN entity.
In an additional embodiment of the present invention, a notification to the MS can also be triggered by the CN entity (for example MSC/VLR or SGSN, etc.), i.e. the CN entity initiates ordering of a location update procedure from MS. This scheme includes the following steps of: serving the MS by a first RNC; moving the MS from a first area to a second area wherein service in the first area is controlled by the first RNC, and service in the second area is controlled by a second RNC; serving the MS by the second RNC, the plurality of RNCs being connected to the CN, so that the control of the MS is changed from the first RNC to the second RNC; determining by the CN entity whether the location update is needed base on factors such as configuration of the CN and/or the types of connection that the MS is having, etc.; notifying, by the CN entity, the MS that a location update from the MS should be performed; and updating a location of the MS in the CN. Alternatively, after receiving a notification from the CN entity, it is up to the MS to decide whether the location update should be performed.
In an additional alternative embodiment of the present invention, an update of the location of the MS from an active connection CN entity to a new idle CN entity via an interface between the active connection CN entity and the new idle CN entity when there is a Serving Radio Network Controller (SRNC) relocation. The scheme includes the following steps of: serving the MS by a first RNC; moving the MS from a first area to a second area wherein service in the first area is controlled by the first RNC, and service in the second area is controlled by a second RNC; serving the MS by the second RNC, the plurality of RNCs being connected to the CN, so that the control of the MS is changed from the first RNC to the second RNC; determining by the active connection CN entity whether the location update is needed based on factors such as configuration of the CN which is connected to the plurality of RNCs and/or the types of connection that the MS is having, etc.; and sending update of the location of the MS by the active connection CN entity to the new idle CN entity via an interface between the active connection CN entity and the new idle CN entity. The CN entity can be a MSC/VLR (Mobile Switching Center/Visitor Location Register) or a SGSN (Serving GPRS Support Node, GPRS is General Packet Radio System). Alternatively, the new idle CN entity determines whether the location update is needed. If the location update is needed, the active connection CN entity then sends the location update to the new idle CN entity via the interface between the active connection CN entity and the new idle CN entity.
In a further additional alternative embodiment of the present invention, a SRNC only moves Radio Resource (RR) control into a new RNC (i.e. a second RNC), and an old CN entity (i.e. the active CN entity before changing the RNC) remains control in the Core Network (CN), i.e. the old CN entity is still active after changing the RNC. The control in the CN is changed along with the location update from the MS. Accordingly, without updating from the MS, the old CN entity is active, and the control in the CN is anchored. In this case, the scheme for providing an update to a new CN entity includes the following steps: serving the MS by a first RNC; moving the MS from a first area to a second area, wherein service in the first area is controlled by the first RNC, and service in the second area controlled by a second RNC; a plurality of RNCs being connected to the CN so that the control of the MS is changed to from the first RNC to the second RNC; notifying the MS on the RNC change; and sending update of the location of the MS by the MS into the new and old CN entities.
In the above and many other embodiments, the Core Network entity can be a Mobile Switching Center/Visitor Location Register (MSC/VLR) which serves the Circuit Switched (CS) connections, or a Serving GPRS Support Node (SGSN) which serves the Packet Switched (PS) connections, or an Interworking Unit/SGSN (IWU/SGSN) which serves PS connections in 3G CN entity interworking with 2G CN entity. 3G stands for the 3rd generation cellular system, and 2G stands for the 2nd generation cellular system.
Further in one embodiment of the present invention, a CN entity receiving location update of the MS may serve both an old RNC and a new RNC. In an alternative embodiment, the old RNC and the new RNC are served by different CN entities.
The present invention also provides a mobile telecommunication system. In one embodiment, the system comprises: a Mobile Station (MS); and at least two Radio Network Controllers (RNCs), at least one of the RNCs being arranged to send a notification to the MS in a response to a RNC relocation between the at least two RNCs.
In another embodiment of the present invention, the system comprises: a Mobile Station (MS); at least two Radio Network Controllers (RNCs); and a Core Network (CN), the CN including at least one CN entity, at least one of the RNCs being arranged to send location update of the MS to the one CN entity via an interface between at least one RNC and at least one CN entity in a response to a RNC relocation between the at least two RNCs.
In an additional embodiment of the present invention, the system comprises: a Mobile Station (MS); at least two Radio Network Controllers (RNCs); and a Core Network (CN), the CN including at least one CN entity, the at least one CN entity being arranged to send a notification to the MS in a response to a RNC relocation between the at least two RNCs.
In a further embodiment of the present invention, the system comprises: a Mobile Station (MS); at least two Radio Network Controllers (RNCs); and a Core Network (CN), the CN including at least one CN entity, the at least one CN entity being arranged to send location update of the MS to a second CN entity via an interface between two CN entities in a response to a RNC relocation between the at least two RNCs.
The present invention further provides schemes for providing an inter CN entity handover, such as inter-SGSN handover, in a 3rd generation cellular system, whereby one of the SGSNs is a 2G SGSN or 3G SGSN, and the other one of the SGSNs is a 2G SGSN or 3G SGSN. This is accomplished by firstly determining whether both of the SGSNs are 2G SGSN or 3G SGSN or whether one is 2G SGSN and the other is 3G SGSN, and secondly operating the corresponding inter-SGSN handover.
One advantage of the present invention is that it allows the location update of the MS to be sent to a correct CN entity in a 3rd generation cellular system where there is a Serving RNC relocation.
Another advantage of the present invention is that it allows an inter CN entity handover, such as inter-SGSN handover, in a 3rd generation cellular system whereby the radio related entities in RNCS, BSs, and MSs, etc., are maintained during the inter-SGSN handover. The new SGSN receives all information from the old SGSN while establishing the new SRNC during a RNC relocation.
Other embodiments to implement a method or procedure in accordance with the present invention may include alternative or optional additional aspects. These and various other advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and form a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to accompanying descriptive matter, in which there are illustrated and described specific examples of an apparatus in accordance with the invention.